Hydrogen, the most abundant element in the universe, has great potential as an energy carrier. However, it is highly unstable and dangerous to produce, store, transport, and deploy (due to being extremely flammable and explosive when mixed with oxygen, an abundant element in Earth's atmosphere). Unlike petroleum, hydrogen may be easily generated from diverse energy sources, including: fossil fuels such as coal and natural gas; nuclear power; biomass; and, other renewable energy technologies such as wind, solar, geothermal, and hydroelectric power. Hydrogen is also nonpolluting, forming water as a harmless byproduct during use. Approximately half of the hydrogen produced today is converted to ammonia and used as a fertilizer. The remaining current hydrogen production is used to convert heavy petroleum sources into lighter fractions suitable for use as fuels which are then used in a variety of applications, such as fuel-cell batteries for a variety of consumer and industrial electronics, and in combustion engines for automobiles and heavy machinery. However, the difficulty and significant safety hazards of storing hydrogen has been a challenge to harnessing the many advantages of hydrogen use.
Developing safe, reliable, compact, and cost-effective hydrogen storage technologies is one of the most technically challenging barriers to the widespread use of hydrogen as a form of energy. Hydrogen storage research has focused largely on technologies and systems used onboard a vehicle in an attempt to improve the weight, volume, and cost of current vehicle-based hydrogen storage systems, as well as to identify and develop new technologies that may achieve similar performance, at a similar cost, as gasoline fuel storage systems. This is a challenging goal because hydrogen has physical characteristics that make it difficult to store in large quantities without taking up a significant amount of space. For example, to be competitive with conventional gasoline powered vehicles, hydrogen powered cars are desired that that may travel on the order of 300 miles between fills.
Hydrogen has a high energy content by weight (about three times more than gasoline), but it has a low energy content by volume (about four times less than gasoline). These properties, along with the aforementioned serious safety considerations, make hydrogen a challenge to store, particularly within the size and weight constraints of a vehicle. However, there are many uses for hydrogen today, such as ammonia production and other example uses set forth above. The focus on overcoming problems with hydrogen-powered vehicles may distract from developing improved hydrogen technologies in other areas. Furthermore, some developments for primary purposes other than on vehicles will undoubtedly find use in vehicles as well.
Improved hydrogen storage systems are needed. Hydrogen storage may desirably be safe, low-cost, efficient to transport, and easily interfaced to other hydrogen systems such as hydrogen production systems, hydrogen storage systems, ammonia production systems, and electricity and power production systems such as fuel cells, laptop power supplies, and automobile engines.